"You" are the sponsor, and your context and objectives and measurements are different from "I".

I am the PMO; I respond to my measurements, incentives, and context.

We all notice: there is a gap. Sort of a Mars v. Venus thing. And, who is to manage the gap, a.k.a. the risk, between us? Well, that's why they pay PMO the big bucks! To manage all the risks, whether under their control and influence or not.

Project balance sheet
My icon for this is the "project balance sheet"

"You" are on the left

"I" am on the right

And, I have the risk (gap) on my side

"You" have a top-down more-or-less "fact free" vision of things. "I" do things stick by stick, bottoms up, dealing with the facts and estimates. "You" and "I" never actually agree. But we get the gap close enough to move ahead. And, that's the way it is on Mars and Venus